I think this is a very interesting topic and deserves to be reincarnated as a thread from time to time.

Unfortunately, I don't have a brother so can't comment about my experiences. However, I do have cousins where the younger brother has turned out to be the taller and more masculine looking etc. I don't know about the cocks but I wouldn't be surprised if they followed suit.

I have often wondered what I would feel like if I were the older brother. Especially when you are growing up, you always assume you are the bigger and most developed. There must come a point in time when you notice the overtaking threat and I guess for some it must be a very humiliating thing to happen. I guess it all depends on how confident you are with your own self image. On the other hand it must be both awesome and weird as the younger brother to become taller (etc...) than your older brother. Showing him your cock is twice as big might be a bit of a mean thing to do but kind of funny at the same time!